Fabrication of TiO₂ Coating by Cold Spraying and Evaluation of Its Property

Titanium dioxide (TiO₂) is a promising material for photocatalyst coating. However, it was difficult to fabricate TiO₂ coatings which have excellent photocatalyst property by thermal spray processes. Because anatase phase of TiO₂ transforms into rutile phase under high temperature i.e. the photocatalyst property of TiO₂ declines by heating. In this study, TiO₂ photocatalyst coatings were fabricated by cold spraying. Agglomerated TiO₂ powder with 100% anatase phase was injected into nitrogen or helium gas stream and deposit onto steel substrate. It was possible to fabricate TiO₂ coatings with anatase phase and dense microstructure. The deposition efficiency was increased with gas temperature. The photocatalytic property of the coatings was evaluated by NOx elimination test. From the results, it became clear that cold sprayed TiO₂ coatings had excellent photocatalyst property.